328 The Circulation through the Dog’s Spleen 
It happens also that forcible distention of the spleen, or contraction of 
the muscle of a hyperaemic spleen pulls all of the veins open, even after 
they leave the trabeculae to enter the spleen lobule. So a contraction of 
the muscle of a hyperaemic spleen will tend to close the ampullae of the 
arteries and to open the veins. The effect of this of necessity must be 
to force the blood from the pulp ito the veins, which is always the case. 
When it is once outside of the spleen the valves will prevent its return. 
And I have found that in certain cases the pressure in the splenic vein 
may exceed the arterial, a condition which can be brought about only in 
ease the spleen contraction acts as a pump. In one case the pressure 
in this vein rose to 190 mm. Hg. with the artery closed, i. e., the arterial 
pressure practically at zero (1. ¢., p. 37). 
Objection may be raised against Jaschkowitz’s experiment as an 
argument in favor of an open circulation, for considerable time elapses 
between cutting the nerves and the following hyperaemia and infarction. 
It must still be shown that in the lying animal the blood is constantly 
passing through the pulp, as is the case in the salmon’s spleen. The influ- 
ence of the contraction of the muscle upon the blood in the pulp must 
be removed in other ways. 
In order to bring more evidence to bear upon this question I have 
made four kinds of successful experiments, which prove conclusively 
that practically all of the blood corpuscles pass through the pulp of the 
spleen. 
In the first of these the dog was bled to death and the blood whipped. 
Cannulae were then tied into the splenic artery and vein, after which 
the anastomoses were tied and the spleen removed. The whipped blood 
and spleen were then kept at from 5° to 5° C. for 24 hours. Then the 
blood and spleen were warmed to 37° and the blood was injected into 
the artery with a pulsating pressure from 80 to 100 mm. Hg. In just 
one minute the blood began to flow from the vein. In 5 minutes the 
spleen began to swell a little, which continued slowly until the spleen 
was quite red and of the appearance it has in the living animal. Now 
the flow from the vein was at the rate of 5 cc. a minute, about the same 
as in the living animal. At the end of half an hour the spleen was 
placed carefully in strong formaln. During the whole time of artificial 
circulation the arterial blood was red and the venous blood blue, and 
at no time was there the faintest indication of the contraction of any 
muscle. Next day frozen sections were made and in all cases it was 
found that the pulp was filled with blood, extending freely over into 
the lobular veins, which were gorged. The interlobular veins were net 
so full, for during the whole experiment the vein was freely open, the 
